The invention concerns a radial-axial bearing assembly comprising a radial cylinder roller bearing for supporting radial forces, an outer ring of said radial cylinder roller bearing having a radially inwards directed flange, said radial-axial bearing assembly further comprising a double-direction thrust cylinder roller bearing having raceways formed by a first and a second bearing washer and by said radially inwards directed flange, the first bearing washer being arranged directly adjacent an end face of an inner ring of said radial cylinder roller bearing, and means being provided for eliminating play in the thrust cylinder roller bearing.
A radial-axial rolling bearing of the pre-cited type is known from DE 10 37 775. This combined bearing is intended mainly for the mounting of spindles of machine tools and comprises a double-row cylinder roller bearing for supporting radial forces. The inner ring of this bearing is made with two outer flanges and one central flange. The outer ring of this double-row cylinder roller bearing has an S-shaped configuration, i.e. it has a radially outwards directed flange at one end and a radially inwards directed flange at the other end. The outwards directed flange serves to fix the bearing on a connecting structure. The radially inwards directed flange of the S-shaped outer ring forms the two inner raceways for a double-direction thrust cylinder roller bearing whose outer raceways are formed by two bearing washers. The thrust cylinder roller bearing is pre-stressed by a nut which is placed around the shaft and acts through an intermediate ring.
The main drawback of such a bearing structure is that the elimination of play and the adjustment of pre-stress in the bearing has to be performed by the customer himself with the help of the locknut. If the pre-stress is too high, the bearing can run hot. In the case of an insufficient pre-stress, on the other hand, there is the danger of the inappropriately mounted component impairing the operation of an entire machine. A further drawback of this radial-axial bearing is that additional parts are required for pre-stressing the bearing which means that the locknut and the intermediate ring have to be additionally manufactured. Besides this, the locknut makes it necessary to provide an outer thread in an appropriate region of the shaft to be mounted. It is also possible that additional manufacturing inexactitudes be introduced into the overall structure due to skewing of these components, i.e. the locknut and the intermediate ring. A further drawback, finally, is that due to its S-shape, the outer ring of the radial cylinder roller bearing is very complicated and expensive to manufacture. The same applies to the inner ring of the radial cylinder roller bearing due to its three flanges. Because of all the above-mentioned drawbacks, the manufacture and handling of such a bearing structure is extremely complicated.
It is an object of the invention to provide a combined radial-axial rolling bearing which is easier to manufacture and very much simpler for handling by the customer.
This and other objects and advantages of the invention will become obvious from the following detailed description.
The invention achieves the above objects by the fact that the flange is arranged between the radial cylinder roller bearing and the thrust cylinder roller bearing and thus defines a first raceway for the thrust cylinder roller bearing, the first bearing washer is arranged between two cylinder roller crown rings of the thrust cylinder roller bearing and defines a second and a third raceway for the thrust cylinder roller bearing while the second bearing washer defines a fourth raceway therefor, said second bearing washer being connected to the outer ring of the radial cylinder roller bearing by fixing screws, and a freedom from play in the thrust cylinder roller bearing is effected by the axial dimension of the first bearing washer.
The decisive advantage of the inventive structure is that, due to the connection of the second bearing washer to the outer ring of the radial cylinder roller bearing, the pre-stress of the bearing assembly can be adjusted by the manufacturer. This simplifies handling of such a combined radial-axial bearing for the customer and avoids defects in the bearing that can be caused by an improper adjustment of the pre-stress by the customer. Besides this, such a bearing can be manufactured much more economically because an additional device in the form of a locknut for adjusting the bearing pre-stress and a force-transmitting intermediate ring are no longer required. Moreover, the precision of manufacturing of the bearing assembly as a whole is also improved by the omission of these components because shape defects of the locknut and the intermediate ring (skewed position) are no longer introduced into the overall bearing structure. A further advantage is that the simple shape of the inner and outer rings of the radial cylinder roller bearing results in a much more economic production of the radial cylinder roller bearing so that the cost of production of the entire bearing structure is further reduced.
In a preferred advantageous embodiment of the invention, the inner ring of the radial cylinder roller bearing comprises a rim that is arranged in the vicinity of the flange of the outer ring and oriented in a direction opposite to the flange. This rim assures that the inner ring cannot be pulled out of the bearing arrangement, i.e. a self-retaining assembled unit is created.
According to a further feature of the invention, the inner ring and the first bearing washer are made integrally with each other. This reduces the total number of components of the bearing arrangement and simplifies the assembly of the entire bearing structure.
According to still another feature of the invention, the second bearing washer projects radially outwardly beyond the outer ring and comprises bores in this projecting region for fixing the bearing assembly on a connecting structure.
For a better seating of the entire bearing assembly in a connecting structure, at least a part of the outer peripheral surface of the outer ring is configured as a cylindrical centering surface for concentrically guiding the bearing in a corresponding bore of the connecting structure.
According to still another feature of the invention, a seal is arranged between the outer and the inner ring of the radial cylinder roller bearing. Further features of the invention concern the lubrication of the combined radial-axial bearing. The outer ring comprises an axial lubricant supply bore which communicates with a radial lubricant supply bore. The second bearing washer likewise comprises an axial and a radial lubricant supply bore. Still other features of the invention concern the configuration of the radial-axial bearing assembly with lubricant discharge bores. According to a final feature of the invention, the claimed bearing is used for mounting master cylinders in printing presses.